Existing standard chargers generally have fixed output voltages, such as 5V. However, output currents of these chargers may vary with nominal parameters thereof. The output current of the standard changer may range from 300 mA to 1800 mA.
An exiting standard USB (Universal Serial Bus) charger generally includes four pins: a VBUS pin, a DP pin, a DM pin, and a GND pin. The VBUS pin is an output pin of the USB charger, while the DP pin and the DM pin are two signal pins of the USB charger. When charging a chargeable device, such as a mobile phone or other mobile terminals, via a charger, the chargeable device is adapted to determine whether the present charger is the standard charger by detecting whether the DP pin and the DM pin are shorted. When the present charger is determined as the standard charger, the chargeable device is charged with a preset fixed output voltage.
However, in some circumstances, the charging capability of the charger is not fully used. That is because, the chargeable device is always charged with a preset fixed output voltage, regardless of the output capability of the charger.